Means for dispersing one fluid in another fluid



Jan. 19, 1943. R. G. GUTHRIE EIAL 2,308,751

MEANS FOR DISPERSING ONE FLUID IN ANOTHER FLUID Filed April 24, 1941Patented Jan. 19, 1943 UNITED STATES PATENT OFFICE MEANS FOR DISPERSINGONE FLUID IN AN OTHER FLUTD Application April24, 1941, Serial No.390,086

4 Claims.

The present .invention relates to a means for intimately dispersing onefluid in another fluid. One practical use to which our invention isapplicable is exemplified by a gas washer, although other uses willbereadily apparent to those skilled in the art. The present invention maybe employed in the general field of gas and liquid contact.

Gas washers are generally employed for the purpose of removing one ormore solid or gaseous components, or vapors, from a gaseous fluid. Thepreferred type of such machines is one in which the gaseous fluid isbubbled through a liquid capable of removing-and retaining one orseveral of the components to be removed. The thoroughness of such awashing process is dependent upon the size of the gas bubbles, thedesideraturn being bubbles of exceedingly small size so that a largesurface area compared to volume is brought into contact with the liquid.Also, the time of contact of the gas bubbles with the fluid is dependentupon their size since, the smaller the gas bubbles the longer they willbe in contact with the liquid. If the gaseous fluid is divided intoexceedingly fine bubbles within the body of the liquid, they will havea'small uplifting force, since they only displace a small-amount of theliquid and when this force is'reduced to the order of forces involved insurface tension of the liquid, the bubble finds difliculty in risingthrough the liquid. In present practice, rectifying columns of greatheight are employed, since the gaseous fluid isin the form of relativelylarge bubbles, and in order to attain sufficient surface contact andduration of contact of the gaseous fluid with the liquid, the bubblesare passed through a large number of stages. It follows that a gaseousfluid may be effectively washed with a comparatively small amount ofliquid, if the gas bubbles can be made sufficiently fine to satisfy therequirements of surface area and time of contact of the gaseous fluidand liquid and sufiicient relative movement of the gas and liquid.

The primary object of our invention is the provision of :an improvedmeans whereby gaseous fluid is caused to rise with adequate relativemovement through the washing liquid in the form of gas bubbles of smallsize.

A further object is the provision of means which occupies a small spaceand utilizes a small amount of liquid in washing a gaseous fluid.

A still further object is the provision of means for the purpose notedwhich is of simple and inexpensive construction and which requires acomparatively small amount of power to operate.

The above objects :are attained by providing means comprising animpeller adapted to be rotated in the body of the washing liquid, and asuitable stator or cage which surrounds ,theimpeller. The gaseous fluidto be washed is introduced into the body of the liquid beneath theimpeller, the rotation of which provides a source of energy to break upthe gaseous fluid into bubbles of the required size. 'This ener y is:applied as :centrifugal force. Since centrifugal force is proportionalto mass, and Whenit is considered that the ratio of-the mass of a liquidto the mass of a gas-is generally :of the orderof ,800 to 1, it willbeseen that :thebulk of the gas will be kept close to the axis of rotationof the impeller and the liquid will be thrown outwardly away from theaxis of rotation. However, depending upon the amount of the gaseousfluid introduced andthe turbulent state of the liquid, a certainquantityof the gaseous fluid will become entrained in the, liquid indifferent sizes of bubbles, each .of which will have a lifting forceproportionalto :the volumeof liquid displaced. The lifting force of eachbubble gtends-to cause ittorise upwardly through the liquid and it willbe observed that the larger bubbles will begin to rise more closelyadjacent the periphery of the impeller than the smaller bubbles. Hence,the smaller bubbles will be carried further outwardly before they riseapredetermined distance vertically. Thus by D OViding astator comprisingan annular vertical wall suitably spaced from the periphery of theimpeller, the large size bubbles will rise between the impeller and thewall, and the small-size bubbles will rise outwardly of the wall.Bysuitably spacing .the'annular wall from the impeller, thesmall-size'bubbles which have-a large surface area compared to volumeare per mitted to rise upwardly-through the liquid. By providing thestator with a frusto-conical hood tapering upwardly and inwardly fromthe annular vertical wall and open at its top, the large-size bubblesmay be directed beneath a second impeller and stator wherein the.abovedescribed operation is repeated. Any suitable number of impellersand stators may be providedsothat all of the gaseous fluid will bedischarged into the body of the liquidin sulflciently small-"sizebubbles to assure a thorough-washing ofthe gaseous fluid.

Bearing .the xabove in ,mind, it will be observed that by providing afrusto-conical impeller and suitably arrangingrit within thefrusto-conical hood of the stator, ,a generally downward current iscreated preventing the large-size-gas'bubbles:from.:rising betweenthe.impellerandstator.

Preferably, in this arrangement, the annular wall of the stator extendsdownwardly of the base of the impeller so that a portion of the liquidand entrained gaseous fluid is reflected toward the axis of rotation torepeat the described cycle. In this arrangement, only the exceedinglyfine bubbles escape beyond the annular wall of the stator whence theyare free to rise upwardly through the body of the liquid. Further, wehave found that by making the last referred to impeller substantiallyhollow to provide an inner conical surface, tapering downwardly andoutwardly of the axis of rotation and providing a frusto-conical' willbe observed, therefore, that the large-size hub portion taperingupwardly and outwardly of V the axis of rotation, the turbulence of theliquid and the circulation of the gaseous fluid ismaterially enhancedfacilitating breaking up of the gaseous fluid into small-size bubbles.It will be observed, therefore, that the liquid in which the gaseousfluid is entrained in exceedingly fine bubbles is discharged outwardlyof the stator by centrifugal force and the large-size bubbles, togetherwith a portion of the liquid, is returned to the center to repeat thecycle. An impeller of a certain diameter and rotated at a given R. P. M.will only break up a certain quantity of gas. If an excess is suppliedthe bubble size getting out of the stator will increase. For handlingmore than the possible optimum per impeller, we propose to use a simplecylindrical stator, allowing the quantity of the gas bubbles which willget between the impeller and stator to rise and get into the centercurrent of a suitably arranged second impeller, which is provided withthe above described stator comprising a cylindrical portion andfrusto-conical hood. If the quantity of gaseous fluid to be handled isstill greater any number of appropriate impellers and stators may beemployed. Preferably the impellers are all mounted for rotation about acommon axis.

Now, in order to acquaint those skilled in the art with the manner ofutilizing our invention, we shall describe in conjunction with theaccompanying drawing preferred embodiments thereof as employed in a gaswasher.

In the drawing: 7

Figure 1 is a fragmentary diagrammatic illustration of an apparatusembodying our invention;

Figure 2 is a vertical sectional view, largely diagrammatic, of a gaswasher constructed in accordance with our invention;

Figure 3 is a horizontal sectional view taken on line 33 of Figure 2,looking in the direction indicated by the arrows;

Figure 4; is a vertical sectional view, largely diagrammatic of amodified form of gas washer illustrating the application of ourinvention as applied to a three stage gas washer; and

Figure 5 is a detail sectional view of a modified form of means forintroducing the gaseous fluid into the washing liquid.

Referring now to Figure l, we have illustrate-d, diagrammatically, twodisc impellers I arranged in vertical alignment and mounted upon a shaft2 for rotation about a vertical axis. A stator 3, open at its top andbottom, surrounds each impeller I, and comprises an annular verticalskirt portion l, and a frusto-conical upper hood portion 5 taperingupwardlyof and inwardly toward the axis of rotation of shaft 2. It willbe understood that the impellers I and stators 3 are submerged in a bodyof the washing liquid in a suitable tank or receptacle having a gaseousfluid inlet and'outlet, and a liquid inlet 'and'outlet defines a wallbeyond which gas bubbles of suflibubbles, as shown in the drawing, willbegin to rise immediately beyond the outer periphery of the impeller,and as the bubbles decrease in size they begin to rise farther away fromthe axis of rotation of the impeller. Now the impeller and stator arearranged so that theskirt portion 4 ciently small-size to be thoroughlywashed by passing upwardly through the body of the liquid aredischarged. A suitable gas space is provided above the surface of theliquid for collecting the washed gas. The larger. gas bubbles, i. e.,those which begin to rise within 'the periphery of skirt portion 4 areof such size that the surface area thereof compared to volume is small,and hence would not be adequately washed if they were allowed to risethrough the liquid to the surface thereof. It will be observed that thefrusto-conical hood portion 5 of the lowermost stator will cause theselarge gas bubbles to be directed inwardly toward the shaft 2, so thatthey come into,

contact with a second impeller I immediately 3 above the lowermoststator 3 where the operation just described will again be repeated.Thus, a

plurality of stators and impellers may be ar-.

ranged in a vertical row to assure that all the gas will be dispersed inthe body of the liquid in extremely small-size bubbles. The number anddimensions of impellers and stators required will be dependent upon thevolume of gaseous fluid to be washed. It will be observed that thefineness of the bubbles permitted to escape beyond the periphery of theskirt portion 4 may be controlled by' varying the distance of the skirtpor-,

tion from the axis of rotation of shaft 2.

Reference may now be had to Figure 2,wherein we'have shown a closed tank6 which is adapted to maintain a suitable washing liquid. Inlet andoutlet conduits I and 8, respectively, are, provided in the lowerportion of thertank for admitting and withdrawing the washing liquidfrom, the tank. The washing liquid preferably should be maintained at alevel somewhat below the upper portion of the tank 6 to provide'a gasspace 9. A gas inlet conduit I0 extends through the bottom of the tank6, and a gas outlet conduit II extends through the upper. end of thetank in communication with the gas space 9.

The impeller and stator means of Figure 2 is indicatedgenerally by thereference numeral I2."

A vertically extending shaft I4 is suitably supported for rotation in asupporting'structure comprising a plurality of vertically. extending legmembers I5, from which spider arms H ex-' tend horizontally inwardlytoward the shaft I4. The inner ends of the arm I! are suitably securedin bearing blocks I8," the latter being adapted to rotatably support theshaft I4.= The shaft I4 extends through the upper 'end of the tank andis adapted to be rotated by any suitable means, for example, by theelectric motor;

20. The lower end of each vertically extending leg I5 has a foot portion3I which rests on the bottom of the tank. A hollow frusto-conicalimpeller 22 is suitably secured to the shaft I 4, as by a press fit, orif desired, the impeller may be keyed to the shaft. The impeller 22comprises outer and inner frusto-conical surfaces 23 and 24,respectively, which taper outwardly from and downwardly of the axis ofrotation of the shaft l4, and a frusto-cOnical hub portion 25 whichtapers upwardly from and outwardly of the axis of the shaft 14. A statorsurrounds the impeller 22 and comprises a frusto-conical hood portion 3|and a vertically extending annular skirt portion 34. Suitable bafllemembers 36 are secured to the outer periphery of the depending skirtportion 34, as by welding, and serve as a means for supporting thestator in spaced relation to the impeller. The balile members 36preferably are formed of strips of light sheet metal or other suitablematerial which a will not react with the gaseous fluid and liquid beingused, and are adapted to be secured, one to each of the legs l5, by thenuts and bolts 38, or in any other suitable manner. The stator, byreason of this construction, is adjustably vertically relative to theimpeller 22.

It will be observed that the frusto-conical surface 31 of the stator istapered to conform with the taper of the outer or exterior frustoconicalsurface 23 of the impeller, and the stator is positioned relative to theimpeller so that the surfaces 31 and 38 define a passageway 39 betweenthem.

Now, when gaseous fluid is admitted into the lower end of the tankthrough the conduit I0, the gaseous fluid will bubble through the liquidin the tank until the bubbles come into contact with the surface of thefrusto-conical hub portion 25 of the impeller and will be deflectedagainst the inside frusto-conical surface 24 of the impeller, whencethey will be directed generally downwardly and outwardly of the axis ofrotation of the impeller and against wall 34. Rotation of impeller 22will draw a continuous stream of liquid in through the open top of thestator, and this continuous stream will be directed downwardly throughand rotated in the passageway 39, as indicated by the arrows. It will beobserved that the impeller will cause liquid and gaseous fluid, thelatter being entrained in the fluid in varying sizes of bubbles, to bedischarged outwardly of the axis of rotation of the shaft 14 bycentrifugal force. The extremely small-size gas bubbles, as before, willbe carried beyond the periphery of wall 34 where they are free to riseupwardly through the body of the liquid surrounding the stator and intogas space 9. The large-size bubbles within the periphery of wall 34would normally tend to rise upwardly, but since a continuous stream ofliquid is being drawn downwardly through the passage 39, they do nothave sufficient force to escape upwardly through the passage 39.Further, it will be remembered that liquid containing entrained gaseousfluid in the form of bubbles and the downwardly directed stream ofliquid are both being directed against the wall 34. The cylindrical wall34 causes the large-size gas bubbles to'be broken up or reflectedinwardly toward the center together with a portion of the liquid. Thussome of the large-size gas bubbles will be broken up into suflicientlysmall sizes to be carried beyond the cylindrical wall 34 with the liquidby centrifugal force. The remaining largesize gas bubbles are thusrecirculated, as indicated by the arrows, until they are of sufficientlysmall size to be carried outwardly of the wall 34.

Rotation of the impeller 22 tends to impart a rotary motion to theentire body of washing liquid, and we have found it desirable to providethe ballles 35, previously referred to, which prevent rotary motion ofthe body of liquid surrounding or outside of the stator. The inner andouter frusto-conical surfaces 23 and 24 and hub 25 are preferablysmooth, highly polished surfaces, so that there is little friction ofthese surfaces with the washing liquid. Hence only a minimum amount ofpower is required to rotate the impeller in the liquid.

It is appropriate to point out at this time that the construction justdescribed effects a high degree of turbulence of the liquid andconsequently aids in the entrainment of the gaseous fluid therein.

It has been observed that as the gaseous fluid rises along the shaft it,it comes into contact with the frusto-conical surface of the hub 25. Thelifting force of the gas bubbles is a vertically and upwardly directedforce, and we have found in a device constructed as above described,that if diametrically opposite elements on the surface of revolution ofthe hub portion 25 define an angle of substantially 60, the gaseousfluid will be satisfactorily di ected against the frusto-con icalsurface 24 with minimum friction losses. Also by constructing theimpeller and stator so that the outer and inner frusto-conical surfaces24 and 23 of the impeller and the inside frustoconical surface 31 of thestator are at an angle of substantially 45 to the horizontal frictionlosses with the liquid will be at a minimum. When these surfaces areformed at this angle, a suflicient stream of the liquid is drawndownwardly through passage 39 and adequate deflection of the stream ofgaseous fluid and liquid off of the skirt portion 34 of the stator forthe purposes already described is attained.

Now if it is desired to large volumes of gas which the single impellerand stator, last described, cannot adequately handle, or to assure astill more intimate mixture of the gaseous fluid with the liquid, wepropose to provide a plurality of impellers and stators, as shown inFigure 3. This apparatus comprises a three stage machine with oneimpeller and stator constituting a single stage.

A plurality of impellers 22a, 22b, and 22care suitably fixed to theshaft 4 for rotation thereby. A stator 35' is associated with theuppermost impeller 220, a stator 5c is associated with the intermediateimpeller 22b, and a stator 39" is associated with the lowermost impeller22a. Each of the stators have secured to the outer peripheral portionsthereof bafiles 3% serving the same purpose in this assembly as theembodiment of Figure 2. The several stators are supported in spacedrelation with respect to their respective impellers upon a supportingstructure similar to that previously described, and the prime referencenumerals indicate like or similar parts to those already described. Inthis embodiment of our invention, we have shown the shaft l4 extendingthrough the upper end of the tank 6' and to which a suitable pulleywheel 55 is secured. The pulley wheel may be driven by any suitablesource of power to rotate the shaft M and the several impellers. It willbe seen that the lower stage comprises, the stator 3 which is identicalto the stator 3Q already described, except that in this instance it isinverted so that the frusto-conical portion 3!" extends down-- wardlyand'inwardly of the axis of the shaft M. The impeller 22 associatedtherewith is arranged so that it rotates in the portion thereof definedby the annular skirt 34". The stator 50 comprises an annular verticalskirt portion 52 in which the associated impeller 22a is adapted torotate. The top or uppermost stage is arranged in an identical manner tothe stator and impeller described in connection with Figure 2. It willbe understood that the tank 6' is provided with a suitable base, andliquid inlets and outlets as in Figure 2.

Now, when gaseous fluid is admitted into the tank through the conduit l9it rises upwardly through the open end 49" of the stator 39" around theshaft M. The hub portion 25' and the conical surface 24' of impeller 22acause the gas bubbles to follow a path directed generally downwardly andoutwardly against the conical wall 3|". The impeller and stator are alsocausing a stream of liquid to be directed downwardly, but withrelatively small force since the impeller is rotating within the annularvertical wall portion 34". The gas bubbles rise through this downwardlydirected stream to the intermediate stage comprising the impeller 22band the stator If the gaseous fluid is being admitted in such largequantities that it cannot all be circulated to some extent by thelowermost stage, the excess will simply escape beyond the impeller 22ato the intermediate stage without first being circulated as noted.Obviously any number of stators and impellers may be arranged in a rowas are necessary to prevent the gaseous fluid from bubbling upwardlythrough the receptacle without being broken up into small-size bubblesin at least one of the several stages.

Referring again to the intermediate stage it will be seen that thestator 50 comprises a cylindrical wall member 52' which is supportedadjacent the impeller 22b by means of the bafiies 36 and is adjustablevertically relative to the impeller by means of the nuts and bolts 38.If the stator is positioned as shown in full lines in the drawing, i.e., more closely adjacent the lowermost stator 22a than the uppermoststator 22c, substantially no gas bubbles will be discharged between thelowermost stator and the intermediate stator. This is due to the factthat the annular skirt portion 52 extends downwardly to such an extentthat the gas bubbles cannot escape, but rather will rise upwardlythrough the stream of liquid being directed downwardly by the impeller22b and the stator 5%. With such an arrangement of the several stagessubstantially all of the gaseous fluid will be discharged between theuppermost and intermediate stators. The uppermost stage is identical tothe preceding embodiment described, and the action at this state of theapparatus is the same as has already been described. The force of thestream of liquid being directed downwardly at the uppermost stage isgreater than that of either of the other stages due to the arrangementof the hood portion 3| of the stator 33 and the associated impeller 220so that the gas bubbles cannot pass upwardly beyond the outer peripheryof the impeller 22c and through the passageway 39'.

If the intermediate stator 50 is positioned equidistant of the lowermoststator 39" and uppermost stator 39' small-size gas bubbles will escapeinto the body of liquid between the several stators. Since the severalstators are adjustable relative to their associated impellers, the sizesof the discharge gas bubbles and the places of discharge issubject'tocontrol, within limits, to meet any particular requirement.

We have observed in a device constructed in accordance with thisembodiment of our invention, that the gaseous fluid hugs the shaft M infairly large sizebubbles in passing between the adjacent impellers.

In Figure 4, we have shown a modified form of shaft M for rotatablysupporting one or more impellers 22'. We have conceived that the shaftl4" may be hollow and the gaseous fluid to be washed may be conductedthrough this shaft and introduced into the liquid below the impeller22', through a plurality of small perforations or openings 55 formed inthe end of the shaft. closing the lower open end thereof isa conicalmember 62. ,Gaseous fluid issuing from the apertures 55 in the end ofthe shaft will be directed upwardly by the interior frusto-com'calsurface 63 of member against the hub portion 25', and thereafterthegaseous fluid will be entrained with the liquid and discharged in themanner already described.

While in the above description we have spe cifically disclosed ourinvention in connection with a gas washing apparatus, it will beunderstood that the means of our invention may be employed for otherpurposes. For example, the invention might be readily adaptable to thechlorination of water or other instances in which it is desired to treata liquid with a gaseous fluid. Further, it will appear that theinvention is not limited specifically to diffusing a gaseous fluid in aliquid, since in practice the means dis-.

closed herein may be employed in any method in which intimate mixture ofone fluid with a different fluid is desired, for example, in forming anemulsion.

We claim:

1; In combination, a receptacle adapted to contain a liquid, asubstantially frusto-conical hollow impeller mounted for rotation abouta vertical axis in said receptacle and having an inside frusto-conicalsurface and an outside frusto-conical surface flaring downwardly andoutwardly of said axis, said impeller having a frusto-conical hubportion tapering upwardly and outwardly-of said axis, means for rotatingsaid impeller about said axis, a stator open at its top and bottom andsurrounding said impeller, said stator having a frusto-conical surfaceand a depending substantially vertical annular skirt portion, saidimpeller and said stator being ar-,

ranged so that a continuous rotating stream of liquid is drawndownwardly through the open top of said stator between saidfrusto-conical surface of said stator and said outside frustoconicalsurface of said impeller, means for introducing gaseous fluid into, saidreceptacle below said impellen'said frusto-conical hub portion, saidinside frusto-conical surface of said impeller and said skirt being.adapted'to cause said gaseous fluid to be discharged outwardly of saidaxis of rotation and beyond the open bottom of said stator in the formof minute globules entrained in said stream.

2. In combination, a receptacle adapted to contain a liquid, asubstantially frusto-conical hollow impeller mounted for rotation abouta Secured to the end of the shaft and and outwardly of said axis, meansfor rotating said impeller about said axis, a stator open at its top andbottom and surrounding said impeller, said stator having afrusto-conical surface and a depending vertical annular skirt portion,said impeller and said stator being arranged so that a continuousrotating stream of liquid is drawn downwardly through the open top ofsaid stator between said frusto-conical surface of said stator and saidoutside frusto-c'onical surface of said impeller, means for introducinggaseous fluid into said receptacle below said impeller, saidfrusto-conical hub portion, said inside frusto-conical surface of saidimpeller and said skirt being adapted to cause said gaseous fluid to bedischarged outwardly of said axis of rotation and beyond the open bottomof said stator in the form of minute globules entrained in said stream,and bafile means for preventing rotation of the body of liquid in saidreceptacle surrounding said stream of liquid.

3. In combination, a receptacle adapted to contain a liquid, asubstantially frusto-conical hollow impeller mounted for rotation abouta vertical axis in said receptacle and having an inside frusto-conicalsurface and an outside frusto-conical surface flaring downwardly andoutwardly of said axis, a stator open at its top and bottom andsurrounding said impeller, said impeller and said stator being arrangedso that liquid is drawn downwardly through the open top of said statorbetween the latter and said outside frusto-conical surface of saidimpeller upon rotation of said impeller, and means for introducing fluidinto said receptacle below said impeller, said inside frusto-conicalsurface of said impeller and said stator being adapted to cause saidfluid to become entrained in said liquid and circulated therewith belowsaid impeller upon rotation of the latter.

4. In combination, a receptacle adapted to contain a liquid, a pluralityof substantially rusto-conical hollow impellers spaced vertically andmounted for rotation about a common vertical axis in said receptacle,each of said impellers comprising an outside frusto-conical surface andan inside frusto-conical surface flaring downwardly and outwardly ofsaid axis, a plurality of stators open at their tops and bottoms onesurrounding each of said impellers, said impellers and stators beingarranged so that upon rotation of said impellers liquid is drawndownwardly through the open tops of said stators and between the latterand the outside frusto-conical surfaces of said impellers, and means forintroducing fluid into said receptacle below the lowermost impeller,said inside frusto-conical surfaces of said impellers and said statorsbeing adapted to cause said fluid to become entrained in said liquid andcirculated therewith below said impellers upon rotation of the latter.

ROBERT G. GUTHRIE. OSCAR J. WILBOR.

